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Fermi radii of lithium by positron annihilation.

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Title: Fermi radii of lithium by positron annihilation.
Author: Paciga, John Joseph
Degree Master of Science - MSc
Program Physics
Copyright Date: 1971
Subject Keywords Fermi surfaces; Lithium
Abstract: A positron annihilation experiment involving collinear point geometry is used to make a direct comparison of the k₁₁₀ and k₁₀₀ Fermi radii in a single crystal of lithium. It is found that is k₁₁₀ greater than k₁₀₀ by 5.6 ± 1.2%, in agreement with theory and a phenomenological interpretation of an earlier long slit experiment. The higher momentum components of the positron wavefunction are calculated by a direct method and found to be negligible. On the other hand, a less straightforward estimate based on a flattened Seitz potential shows that the higher momentum components of the electron wavefunction significantly reduce the experimentally observed anisotropy. Hence, the difference of 5.6% should be regarded as an upper limit on the true distortion of the Fermi surface of lithium.
URI: http://hdl.handle.net/2429/33892
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]
Scholarly Level: Graduate

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